Rubber composition and method of preserving rubber



Patented Nov. 2, 1937 UNITED STATES PATENT "or-mg RUBBER ooMRosrrron 1 AND METHOD or PRESERVING RUBBER Waldo. L; Scmon, Silver LaketVillage, Ohio, as-

signor to'The B. F. Goodrich Company, New York, N.'Y., a corporation of New York No Drawing. Original application March20, 1931,

Serial No. 524,217. Dividedwand this applica tion March 26, .1935; SeriaLNo. 13,086

6 Claims. (Cl.'18'50) This invention relates to amethod of producing a rubber composition having high resistance to deterioration under the influence of heat, light and exposure to air, and'to a rubber composition to introduce into the rubber mix before vulcanization materials generally classified under the term anti-oxidantsfi A purpose of the present invention is to provide an anti-oxidant which shallbe more effective in retarding the deterioratil. g influences hereinabove referredto and. which shall be economical to manufacture and which need be used only in relatively small proportions in the rubber mix. I

Ihave found that substances which are atthe including thioethers, are particularly efiective in retardingdeterioration of rubber compositions in which they are incorporated. Although it is to be understood that these anti-oxidants may be used to prevent the deterioration and hardening of crude rubber in storage, they find their greatest usefulness when employed in conjunction with vulcanized rubber articles to increase the normal period of their usefulness. The preferred substances of this invention are compounds containing only hydrocarbon groups attached to the secondary amino group and to the ether oxygen or sulphur; but neutral or basic substituents such as hydroxy groups, primary or tertiary amino groups, etc. may be present if desired. Strongly acidic groups such as carboxyl or sulphonic acid groups, or other substituents containing doubly bound oxygen, should be avoided, however, as they tend greatly to reduce the anti-oxidant power of the compounds.

The class of compounds described above includes, for example, p-methoxy diphenylamine, o-methoxy diphenylamine, m-methoxy diphenylamine, p-methoxy phenyl naphthylamine, p-methoxy phenyl biphenylamine, phenylamino methyl naphthol, methoxy phenyl toluidine, p,p'- dimethoxy diphenylamine, ethoxy diphenylamine, butoxy diphenylamine, benzoxy diphenlyamine, p-phenyl amino diphenylether, p-naphthylamino diphenylether, p,p '-di(phenylamino) diphenylsame time secondary aromatic amines and ethers;

ether, o,o,- diiphenylamino) diphenylether, p,pf -di(phenylamino) diphenyl sulphide, dibenzyl diamino diphenyl ether, diphenyl-"diamino diethyl sulphide, dinaphthyl diamino diethyl sulphide, dinaphthyl diamine,.diphenyl sulphi dinaphthyl diamino diphenylether, diphenyl diamino diethylether, diphenyl diamino dibenzyl ether, dinaphthyl diamino, diethylether, dianisyl ethylene diamine, dianisyl phenylene diamine, p-phenylamino p dimethylamino diphenylether, mononaphthyldiaminodiphenylether, dianisyl diamino diphenylether, ethyl mercapto-diphenylamine, diphenyl dianisidine,. methoxy p-iso-; propenyl diphenylamine,. p.-isop ropenylphenylamino diphenylether, etc.

When incorporated into. rubber compositions before vulcanization, preferably in the proportions of from M1130 5% ofithe rubber? content of the composition, the anti-oxidants of this, inven-.. tion areextremelyeffective in retarding their deteriorations, compositions so treated being capable of withstandingthe deleterious effect of exposure-to oxidizing materials or to the elements for a far longer period than similar unblack 40 parts, mineral rubber 10 parts, palm oil 5 parts, and hexamethylene tetramine 0.75 part, The composition was divided into portions, certain of which were used as controls. Into theother portions were mixed ,a further 0.95 part (0.5% of the weight of the composition) of one of the above-described class of antioxidants. The compositions were thoroughly mixed, and vulcanized in a press for minutes at 145 0. (294 F.) to produce an optimum cure.

The relative rate of aging of the vulcanized compositions were compared by measuring their respective tensile strengths andelongations before and after aging. Accelerated aging tests were carried out in the Geer aging oven, in which samples were maintained at a temperatureof "70 C. (158 F.) in a constantly renewed stream of air, as well as in the Bierer-Davis bomb, in which other samples were maintained at the same temperature (70 C.) in an atmosphere of oxygen at a pressure of 300 lbs. per square inch. Theresults obtained are given in the following table in which T indicates ultimate tensile strength in pounds per square inch and E indicates ultimate elongation in per cent. of original length. Each of the tests is accompanied by a control test. of the composition without the anti-oxidant.

erwise limited, is employed in the claims in a. ge-

neric sense to include both oxygen ethers and thioethers.

This application is a division of my copending application Serial No. 524,217 filed March 20,

Aging tests After 48 hours in Before aging 32 623 35 the BlifrergD avis e om Anti-oxidant r '1 E l E None (control) a, 629 650 1, 992 450 615 247 Crude diphenyl diamino diethyl sulphide 832 670 2, 565 507 2, 076 537 Crude dinaphthyl diamino diethyl sulphide 3, 729 673 2, 591 507 1, 868 523 None (control) 3, 350 603 1,890 447 790 297 Crude diphenyl diamino diethylether-- 3, 676 650 2, i320 517 1, 770 493 None (control) 630 636 267 Dinaphthyl diamino diphenyletheiz 3, 650 657 2, 081 620 None (control) 3, 512 620 1, 828 427 1,074 377 Dinaphthyl diamino diplienyl sulphide 3, 527 787 2, 615 543 2, 617. 583 None (control) 3, 739 1, 162 427 p-Methoxy diphenylamine 3, 746 2, 802 586 None (control) .Q 3, 665 520 235 p-Ethoxy diphenylamine 3, 536 2, 595 i 585 p-Ethoxy phenyl naphthylamiue 3, 620 2, 750 615 than those here specifically disclosed. The proportions of the constituents may be varied, or'

other substances may be substituted generally therefor, since this invention is applicable-to pure rubber compositions of the most varied nature.

It is understood that the term treating as employed in the appended claims is used in-a generic sense to include either the incorporation of the anti-oxidants into the rubber by milling or similar process, or their addition to the rubber latex before the coagulation, or to the application thereof to the surface of a mass of crude or vulcanized rubber. The term rubber is likewise employed in the claims in a generic sense to include caoutchouc, whether natural or syn thetic, reclaimed rubber, balata, gutta percha,

rubber isomers and like products, whether or not admixed with fillers, pigments, vulcanizing or accelerating agents. The term ether, unless oth- While I have herein disclosed certain preferred manners of performing my invention, I do not thereby desire or intend to limit myself solely thereto, for, as hitherto stated, the precise proportions of the materials utilized may be varied 7 and other materials having equivalent chemical properties may'b'e employed if desired without departing from the spirit andfscope of the invention as defined in the appended claims.

I claim:

1. The method of preserving rubber which comprises treating rubber with an aromatic dionly by a single alkoxy-aryl group.

2. The method of preserving rubber which comprises treating rubber with phenylene diamine in which eachamino group is substituted only by a single alkoxy-aryl group.

- 3. The method of preserving rubber which comprises treating rubber with N,N' dianisyl phenylene diamine. V

4. A rubber compositionoomprising rubber and an aromatic diamine in which each amino group is substituted only by a single alkoxy-aryl group.

5. A rubber composition comprising rubber and an arylene diamine in which each amino group is substituted'only by a single alkoxy-aryl group.

6; A' rubber composition comprising rubber and N,N dianisyl phenylene diamine.

WALDO L. SEMON.

amine in which each amino group is substituted 7 

